Generally, .step command to sweep the parameter of a part.
Sometimes, need to “do not stuff” a part and to compare the gap. For example, 1) “do not stuff” a cap; 2) “do not stuff” a resistor, compare the waveform.
Is it possible to add history depth, eg 2, it‘s convenient for circuit debug and parameter change. Compare the latest simulation result. Something like this:
The usual technique for a capacitor is to do a .step over it’s value where one value is zero. Same for a resistor but the value would be, e.g., 1T, when it’s not stuffed.
Overlaying multiple simulations is a bit of an issue because (i) it complicate accessing the data(QSPICE implements and manages its own 64 bit virtual address space) and (ii) potentially reduces the integrity of plotting data from the current schematic.
–Mike
Got it,Thanks for your explanation. 
